U.S. patent application number 10/875984 was filed with the patent office on 2005-03-31 for photoresist composition.
This patent application is currently assigned to HYNIX SEMICONDUCTOR INC.. Invention is credited to Jung, Jae Chang.
Application Number | 20050069807 10/875984 |
Document ID | / |
Family ID | 34374224 |
Filed Date | 2005-03-31 |
United States Patent
Application |
20050069807 |
Kind Code |
A1 |
Jung, Jae Chang |
March 31, 2005 |
Photoresist composition
Abstract
Disclosed herein are photoresist compositions, methods of
forming photoresist patterns using the compositions, and
semiconductor devices made by the methods. The negative photoresist
composition includes a photoresist polymer having a polymerization
repeating unit and a melamine derivative as a cross-linking agent,
which prevents the collapse of photoresist patterns formed at a
thickness of less than 50 nanometers (nm). Accordingly, the
disclosed negative photoresist compositions are useful in a
photolithography process, especially in those processes using EUV
(Extreme Ultraviolet, 13 nanometers).
Inventors: |
Jung, Jae Chang; (Seoul,
KR) |
Correspondence
Address: |
MARSHALL, GERSTEIN & BORUN LLP
6300 SEARS TOWER
233 S. WACKER DRIVE
CHICAGO
IL
60606
US
|
Assignee: |
HYNIX SEMICONDUCTOR INC.
Gyeonggi-do
KR
|
Family ID: |
34374224 |
Appl. No.: |
10/875984 |
Filed: |
June 24, 2004 |
Current U.S.
Class: |
430/270.1 |
Current CPC
Class: |
G03F 7/0382
20130101 |
Class at
Publication: |
430/270.1 |
International
Class: |
G03C 001/76 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 29, 2003 |
KR |
10-2003-0067497 |
Claims
What is claimed is:
1. A photoresist composition comprising a photoresist polymer
including a polymerization repeating unit represented by Formula 1,
a cross-linking agent represented by Formula 2, a photoacid
generator and an organic solvent: 4wherein R.sub.1, R.sub.2 and
R.sub.3 are individually hydrogen or a methyl group; R.sub.4 is a
linear or branched C.sub.1-C.sub.10 alkylene group; R.sub.5 is an
acid labile protecting group; R.sub.6, R.sub.7, R.sub.8, R.sub.9,
R.sub.10, and R.sub.11 are individually a linear or branched
C.sub.1-C.sub.10 alkyl or C.sub.1-C.sub.10 alkoxy group; and
a:b:c=30-60 mol %:20-50 mol %:5-30 mol %.
2. The photoresist composition according to claim 1, wherein the
cross-linking agent is present in an amount ranging from 5 wt % to
30 wt % based on the weight of the photoresist polymer.
3. The photoresist composition according to claim 1, wherein the
acid labile protecting group is selected from the group consisting
of t-butyl, tetrahydropyran-2-yl, 2-methyl tetrahydrophyran-2-yl,
tetrahydrofuran-2-yl, 2-methyl tetrahydrofuran-2-yl,
1-methoxyprophyl, 1-methoxy-1-methylethyl, 1-ethoxypropyl,
1-ethoxy-1-methylethyl, 1-methoxyethyl, 1-ethoxyethyl,
t-butoxyethyl, 1-isobutoxyethyl and 2-acetylmenth-1-yl, and
2-methyl adamantyl.
4. The photoresist composition according to claim 1, wherein the
polymerization repeating unit of Formula 1 is poly(9-anthracene
methyl methacrylate/methyl methacrylate/acrylic acid) and the
cross-linking agent is represented by Formula 2a or 2b: 5
5. The photoresist composition according to claim 1, wherein the
photoacid generator is one or more compounds selected from the
group consisting of diphenyl iodide hexafluorophosphate, diphenyl
iodide hexafluoroarsenate, diphenyl iodide hexafluoroantimonate,
diphenyl p-methoxyphenylsulfonium triflate, diphenyl
p-toluenylsulfonium triflate, diphenyl p-isobutylphenylsulfonium
triflate, diphenyl p-t-butylphenylsulfonium triflate,
triphenylsulfonium hexafluorophosphate, triphenylsulfonium
hexafluoroarsenate, triphenylsulfonium hexafluoroantimonate,
triphenylsulfonium triflate, dibutylnaphthylsulfonium triflate,
phthalimidotrifluoromethane sulfonate, dinitrobenzyltosylate,
n-decyl disulfone, and naphthylimido trifluoromethane
sulfonate.
6. The photoresist composition according to claim 1, wherein the
photoacid generator is present in an amount ranging from 2 wt % to
10 wt % based on the weight of the photoresist polymer.
7. The photoresist composition according to claim 1, wherein the
organic solvent is selected from the group consisting of methyl
3-methoxypropionate, ethyl 3-ethoxypropionate, propyleneglycol
methylether acetate, cyclohexanone, 2-heptanone, ethyllactate, and
mixtures thereof.
8. The photoresist composition according to claim 1, wherein the
organic solvent is present in an amount ranging from 700 wt % to
4000 wt % based on the weight of the photoresist polymer.
9. A process for a photoresist pattern formation, the process
comprising the steps of: (a) coating the photoresist composition of
claim 1 on a wafer to form a photoresist film; (b) exposing the
photoresist film to light; and, (c) developing the exposed film to
form a photoresist pattern.
10. The process according to claim 9, further comprising the steps
of performing a soft baking step before the step (b) and a post
baking process after the step (b).
11. The process according to claim 9, wherein the light source is
selected from the group consisting of EUV, KrF, ArF, VUV, E-beam,
X-beam, and ion beam.
12. A semiconductor device manufactured by the process according to
claim 9.
Description
BACKGROUND
[0001] 1. Technical Field
[0002] The present invention relates to photoresist compositions.
More specifically, it relates to photoresist polymers and
photoresist compositions comprising the same, which are suitable
for a photolithography process using a light source of a far
ultraviolet region such as EUV (Extreme Ultraviolet, 13 nanometers)
in fabrication of microfine circuits of a high-integrated
semiconductor device.
[0003] 2. Description of the Related Art
[0004] Recently, chemical amplification type DUV photoresists have
been investigated in order to achieve high sensitivity in microfine
circuit formation processes for preparing semiconductor devices.
Such photoresists are prepared by mixing a photoacid generator and
a matrix polymer having an acid labile structure.
[0005] According to reaction mechanism of such a photoresist, the
photoacid generator produces acid when it is illuminated by a light
source, and the main chain or branched chain of the matrix polymer
reacts with the generated acid in the baking process and is
decomposed or crosslinked, so that polarity of the polymer is
considerably altered. This alteration of polarity results in a
solubility difference in a developing solution between an exposed
area and an unexposed area. For example, in case of a negative
photoresist, acid is generated in the exposed area and the main or
branched chain of the polymer causes cross-linking reaction by the
generated acid and becomes insoluble. As a result, the polymer is
not dissolved in a subsequent development process, thereby forming
a negative image of a mask on a substrate.
[0006] In the photolithography process, resolution depends upon
wavelength of a light source. As the wavelength of light source
becomes smaller, the more microfine patterns may be formed. For
exposure equipment required for pattern formation of less than 50
nanometers (nm), Extreme Ultraviolet (EUV) equipment is under
development, and photoresist materials are also under development.
For the photoresists, there is a significant problem that pattern
collapse may occur in formation of the photoresist pattern having a
thickness of less than 50 nm. Therefore, negative photoresists are
required rather than positive photoresists to prevent collapse of
photoresist patterns.
SUMMARY OF THE DISCLOSURE
[0007] Accordingly, negative photoresist compositions are disclosed
which are useful for a photolithography process using EUV to form
less than 50 nm microfine patterns. Specifically, disclosed herein
is a photoresist composition comprising a photoresist polymer
including a polymerization repeating unit represented by Formula 1,
a cross-linking agent represented by Formula 2, a photoacid
generator and an organic solvent: 1
[0008] R.sub.1, R.sub.2 and R.sub.3 are individually hydrogen or a
methyl group;
[0009] R.sub.4 is a linear or branched C.sub.1-C.sub.10 alkylene
group;
[0010] R.sub.5 is an acid labile protecting group;
[0011] R.sub.6, R.sub.7, R.sub.8, R.sub.9, R.sub.10, and R.sub.11
are individually a linear or branched C.sub.1-C.sub.10 alkyl or
C.sub.1-C.sub.10 alkoxy group; and
[0012] a:b:c=30-60 mol %:20-50 mol %:5-30 mol %.
[0013] Processes for forming a photoresist pattern by using the
above-mentioned photoresist composition are also disclosed. One
such process includes the steps of coating the photoresist
composition on a wafer to form a photoresist film, exposing the
photoresist film to light, and developing the exposed film to a
photoresist pattern.
[0014] Semiconductor devices produced by using the above-mentioned
photoresist compositions are also disclosed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a NMR spectrum of a photoresist polymer according
to the present invention.
[0016] FIG. 2 is a photograph illustrating a photoresist pattern
formed by using a photoresist composition of the present
invention.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
[0017] The present invention provides a negative photoresist
composition comprising a photoresist polymer including a
polymerization repeating unit represented by Formula 1; a
cross-linking agent represented by Formula 2; a photoacid
generator; and an organic solvent.
[0018] In the photoresist composition, a melamine derivative is
present in an amount ranging from 5 weight per cent (wt %) to 30 wt
% based on the weight of the photoresist polymer as a cross-linking
agent. 2
[0019] wherein
[0020] R.sub.1, R.sub.2 and R.sub.3 are individually hydrogen or a
methyl group;
[0021] R.sub.4 is a linear or branched C.sub.1-C.sub.10 alkylene
group;
[0022] R.sub.5 is an acid labile protecting group;
[0023] R.sub.6, R.sub.7, R.sub.8, R.sub.9, R.sub.10, and R.sub.11
are individually a linear or branched C.sub.1-C.sub.10 alkyl or
C.sub.1-C.sub.10 alkoxy group; and
[0024] a:b:c=30-60 mol %:20-50 mol %:5-30 mol %.
[0025] The acid labile protecting group is a group which may be
separated by acid. The group prevents the photoresist compound from
dissolving in an alkaline developing solution. If the acid labile
protecting group is separated by acid generated by the light
exposure, the photoresist compound may be dissolved in the alkaline
solution.
[0026] The acid labile protecting group can be any of the known
protective groups including, for example, the conventional acid
labile protecting groups disclosed in U.S. Pat. No. 5,212,043 (May
18, 1993), WO 97/33198 (Sep. 12, 1997), WO 96/37526 (Nov. 28,
1996), EP 0 794 458 (Sep. 10, 1997), EP 0 789 278 (Aug. 13, 1997),
U.S. Pat. No. 5,750,680 (May 12, 1998), U.S. Pat. No. 6,051,678
(Apr. 18, 2000), GB 2,345,286 A (Jul. 5, 2000), U.S. Pat. No.
6,132,926 (Oct. 17, 2000), U.S. Pat. No. 6,143,463 (Nov. 7, 2000),
U.S. Pat. No. 6,150,069 (Nov. 21, 2000), U.S. Pat. No. 6,180,316 B1
(Jan. 30, 2001), U.S. Pat. No. 6,225,020 B1 (May 1, 2001), U.S.
Pat. No. 6,235,448 B1 (May 22, 2001), and U.S. Pat. No. 6,235,447
B1 (May 22, 2001). Preferably, the acid labile protecting group can
be selected from the group consisting of t-butyl,
tetrahydropyran-2-yl, 2-methyl tetrahydrophyran-2-yl,
tetrahydrofuran-2-yl, 2-methyl tetrahydrofuran-2-yl,
1-methoxyprophyl, 1-methoxy-1-methylethyl, 1-ethoxypropyl,
1-ethoxy-1-methylethyl, 1-methoxyethyl, 1-ethoxyethyl,
t-butoxyethyl, 1-isobutoxyethyl and 2-acetylmenth-1-yl and 2-methyl
adamantyl.
[0027] The polymerization repeating unit of Formula 1 includes an
anthracene monomer having excellent etching resistance.
[0028] Preferably, the polymerization repeating unit of Formula 1
is poly(9-anthracene methyl methacrylate/methylmethacrylate/acrylic
acid) and the melamine derivative of the Formula 2 can preferably
be selected from the compounds of Formula 2a or 2b. 3
[0029] The photoresist composition of the present invention further
comprises an organic solvent and a photoacid generator in addition
to the photoresist polymer and the cross-linking agent.
[0030] Any conventional photoacid generators capable of producing
acid by the light exposure can be used, which includes some of
conventional photoacid generators disclosed in U.S. Pat. No.
5,212,043 (May 18, 1993), WO 97/33198 (Sep. 12, 1997), WO 96/37526
(Nov. 28, 1996), EP 0 794 458 (Sep. 10, 1997), EP 0 789 278 (Aug.
13, 1997), U.S. Pat. No. 5,750,680 (May 12, 1998), U.S. Pat. No.
6,051,678 (Apr. 18, 2000), GB 2,345,286 A (Jul. 5, 2000), U.S. Pat.
No. 6,132,926 (Oct. 17, 2000), U.S. Pat. No. 6,143,463 (Nov. 7,
2000), U.S. Pat. No. 6,150,069 (Nov. 21, 2000), U.S. Pat. No.
6,180,316 B1 (Jan. 30, 2001), U.S. Pat. No. 6,225,020 B1 (May 1,
2001), U.S. Pat. No. 6,235,448 B1 (May 22, 2001), and U.S. Pat. No.
6,235,447 B1 (May 22, 2001). Sulfide type or onium type compounds
are mostly preferred for the photoacid generator.
[0031] The photoacid generator can be one or more compounds
selected from the group consisting of diphenyl iodide
hexafluorophosphate, diphenyl iodide hexafluoroarsenate, diphenyl
iodide hexafluoroantimonate, diphenyl p-methoxyphenylsulfonium
triflate, diphenyl p-toluenylsulfonium triflate, diphenyl
p-isobutylphenylsulfonium triflate, diphenyl
p-t-butylphenylsulfonium triflate, triphenylsulfonium
hexafluorophosphate, triphenylsulfonium hexafluoroarsenate,
triphenylsulfonium hexafluoroantimonate, triphenylsulfonium
triflate, dibutylnaphthylsulfonium triflate,
phthalimidotrifluoromethane sulfonate, dinitrobenzyltosylate,
n-decyl disulfone, and naphthylimido trifluoromethane sulfonate.
Here, the photoacid generator is preferably present in an amount
ranging from 2 wt % to 10 wt % based on the weight of the
photoresist polymer. It has been found that the photoacid generator
lowers photosensitivity of the photoresist composition when used in
the amount of less than 2 wt %. However, when used in the amount of
more than 10 wt %, the photoacid generator absorbs far ultraviolet
rays and generates a large amount of acid, resulting in formation
of a pattern with poor profile.
[0032] Any of conventional organic solvent can be used in the
photoresist composition, including some of the conventional
solvents disclosed in the documents described above. Preferably,
the organic solvent is selected from the group consisting of methyl
3-methoxypropionate, ethyl 3-ethoxypropionate, propyleneglycol
methylether acetate, cyclohexanone, 2-heptanone, ethyl lactate, and
mixtures thereof. Here, the organic solvent is present in an amount
ranging from 700 wt % to 4000 wt % based on the weight of the
photoresist polymer to obtain a photoresist film having a desired
thickness.
[0033] The present invention also provides a process for
photoresist pattern formation, which includes the steps of coating
the photoresist composition of the present invention on a top
portion of an underlying layer to form a photoresist film, exposing
the photoresist film to light, and developing the exposed film to
form a photoresist pattern.
[0034] The process for forming a photoresist pattern can also
include the steps of performing a soft-baking step before the
photoresist film is exposed to light and a post-baking step after
the photoresist film is exposed to light. Preferably, the baking
step is performed at a temperature ranging from 70.degree. C. to
200.degree. C.
[0035] The exposure process is preferably performed by using a
light source selected from the group consisting of EUV, KrF, ArF,
VUV, E-beam, X-beam, and ion beam.
[0036] The developing process can be performed using alkaline
developing solution. TMAH aqueous solution ranging from 0.01 wt %
to 5 wt % can preferably be used.
[0037] The reaction mechanism of the negative photoresist according
to the present invention is as follows: The photoacid generator
produces acid when it is exposed to ultraviolet rays from the light
source. In the baking process after exposure, the acid reacts with
the polymer comprising the repeating unit of Formula 1 to cause
cross-linking reaction by the melamine derivative of Formula 2 as a
cross-linking agent. As a result, the polymer can no longer be
dissolved in the subsequent developing process. However, since the
cross-linking reaction does not occur in the unexposed area, the
polymer is dissolved in the subsequent process, thereby forming a
negative image of a mask on the substrate.
[0038] In addition, the present invention provides a semiconductor
device manufactured by the photoresist composition of the present
invention.
[0039] Hereinafter, the present invention will be described in more
detail by the specific examples. However, they are just the
examples and are not intended to limit the scope of the present
invention.
EXAMPLE 1
Preparation of Photoresist Polymer
[0040] Four grams (g) of 9-anthracene methyl methacrylate, 2 g of
methyl methacrylate, 4 g of acrylic acid and 0.2 g of AIBN were
dissolved in 50 g of a mixture solvent of 25 g of tetrahydrofuran
and 25 g of methylethylketone, and the resulting mixture was
reacted at 66.degree. C. for 8 hours. After the reaction, the
resulting mixture was precipitated in ethylether, filtered, and
vacuum-dried, thereby obtaining poly(9-anthracene methyl
methacrylate/methyl methacrylate/acrylic acid) having a molecular
weight of 17,500 (yield: 86 %) (see the NMR spectrum of FIG.
1).
EXAMPLE 2
Preparation of Negative Photoresist Composition
[0041] One gram of poly(9-anthracene methyl methacrylate/methyl
methacrylate/acrylic acid) obtained from Example 1, 0.1 g of the
melamine derivative of Formula 2a and 0.05 g of triphenylsulfonium
trifate as an acid generator were dissolved in 20 g of
cyclonehexanone as an organic solvent. The resulting mixture was
filtered through a filter with a 0.20 micrometer (.mu.m) pore size,
thereby obtaining a photoresist composition of the present
invention.
EXAMPLE 3
Photoresist Pattern Formation
[0042] The photoresist composition obtained from Example 2 was
spin-coated on a silicon wafer with 0.13 .mu.m thickness, and baked
at about 130.degree. C. for 90 seconds. After baking, the
photoresist film was exposed to light using an ArF laser exposer
(ASML Co., Ltd), and then post-baked at about 130.degree. C. for 90
seconds. When the post-baking was completed, it was developed in a
2.38 wt % TMAH solution for about 40 seconds, to obtain 130 nm L/S
pattern without collapse (see FIG. 2).
[0043] As discussed hereinbefore, microfine patterns can be
obtained by using the negative photoresist composition of the
present invention comprising a melamine derivative as a
cross-linking agent and a polymer which causes cross-linking
reaction by the cross-linking agent. Specifically, the photoresist
composition of the present invention is useful for a
photolithography process using EUV to form photoresist patterns of
less than 50 nm thickness.
* * * * *